Forces loyal to Libyan leader Moammar Gadhafi launched an intense, all-day bombardment on the port area of rebel-held Misrata Tuesday, in a surprise assault against the city's sole lifeline to the world.

At least three African migrant workers were reported killed and up to 20 wounded in the shelling. They were among at least 1,500 migrants, mainly from Niger, awaiting evacuation from Misrata.

The fighting forced a ship chartered by the International Organization for Migration to wait offshore. The Albanian passenger ferry, Red Starr 1 is carrying 10 shipping containers of aid and two ambulances for the battered city.

Rebel officials in Misrata said they alerted NATO, which responded late Tuesday by pounding pro-government targets in desert terrain east of the city.

Loyalist forces also continued military strikes on ethnic Berber towns in the western mountains region Tuesday.

The commander of NATO operations in Libya, Lieutenant General Charles Bouchard, denied government claims that an allied airstrike late Sunday in a complex where Mr. Gadhafi lives was an assassination attempt.

Russian President Vladimir Putin accused the coalition of straying from the U.N. mandate to protect civilians. Without naming them, he said certain "officials" had reversed earlier claims that they were not targeting Mr. Gadhafi.

Earlier Tuesday, Russian Foreign Minister Sergei Lavrov said Moscow would not support any U.N. Security Council resolution that might escalate the conflict. Last month, Russia abstained from voting on a resolution authorizing the no-fly zone over Libya to protect civilians.

At a meeting in the Ethiopian capital Addis Ababa, Libya called on the African Union to hold an emergency summit to discuss how to deal with Western airstrikes.

Libyan Foreign Minister Abdelati Obeidi said the 53-nation AU should invoke its mutual defense pact in response to the strikes. Obeidi and rebel representatives have been meeting separately with AU officials in Addis Ababa to discuss an end to the war.

The AU has proposed a solution calling for an immediate cessation of hostilities followed by a transitional period and political dialogue. The rebels rejected the plan earlier this month, saying any settlement must include the departure of Mr. Gadhafi and his sons. The AU's commissioner for peace and security, Ramtane Lamamra, accused the West of failing to support the bloc's peace proposal.